Electric control circuit and recorder



Oct. 13, 1953 G. w. BARNES, JR

ELECTRIC CONTROL CIRCUIT AND RECORDER 8 Sheets-Sheet l original Filed April 12, 1944 FIG.

R. .J R S mm. E R V A ma.. W E G R O E G ATTORNEY.

Oct. 13, 1953 u" IIII n INVENTOR. GEORGE'W. BARNES JR.

MMM

ATTORNEY.

Oct. 13, 1953 G. w. BARNES, .JR 2,655,426

y ELECTRIC CONTROL CIRCUIT AND RECORDER original med April 12, 1944 8 Sheets-Shes?. 3

95 |97 |96 F l G' 32| los JNVENTOR. 4GEORGE w. BARNES JR.

ATTORNEY.

Oct. 13, 1953 E G. w. BARNES, JR 2,655,426

ELECTRIC CONTROL CIRCUIT AND RECORDER I origin'al Filed April 12/, 1944 "5 "7 ATTORNEY.

Oct. 13, 1953 Original Filed April 12, 1944 G. W. BARNES, JR

ELECTRIC CONTROL CIRCUIT AND RECORDER GEORGE W. BARNES JR.

ATTORNEY.

Oct. 13, 1953 G. w. BARNES, JR

ELECTRIC CONTROL CIRCUIT AND RECORDER s sheets-shes@ Original Filed April l2, 1944 R. .J RS mE N ma WA W G E l G F R O E G wm h m nl@ o. w W. 5 g @Ao 4, f 4.F L U l l l I I I l l l I Ilm L |Wb3 o .nl om M15 1 l 1 l l l l x r l |6 l@ l l I l l I l inw CRL WIL@ u, n :m N

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ATTOR NEY.

Patented Oct. 13, 1953 UNITED STATES PATENT OFFICE ELECTRIC CONTROL kCIRCUIT AND RECORDER George `W. Barnes, Jr., Clifton Heights, Pa., assignor, by mesne assignments, to Minneapolis- Honeywell Regulator Company, Minneapolis, Minn., a corporation of Delaware Claims. 1

The present invention relates to recording in.- struments, and more particularly recording in.- struments that are used to make simultaneously records of the Values of two conditions on rectangular coordinates.

In most recording instruments the value of a single condition is recorded against time by moving a marking element in one direction and moving the chart upon which the record is made at right angles thereto and at a constant speed. There are times, however, where it is more desirable to record the value of one condition with respect to the value of a second. In such a case a more complicated instrument is necessary since means must be provided for moving the marking element in two directions.

This application is a division of my copending application, Serial Number 530,611, led April 12, 1944, now Patent 2,527,207,issued October V24, 1950. rected to the combination of an electric control circuit and a recorder.

It is an object of the invention to provide an instrument in which the values of a plurality of variable conditions may be recorded simultaneously with a single recording element. It is a further object of the invention to provide an instrument in which a recording element is moved in one direction in response to variations in the value of one condition and in which the recording element is moved in a direction at right angles to the rst direction-in response to variations in the value of a second condition. y

It is a further object of thevinvention to provide an instrument in which the value of one condition may be successively plotted against the values of a plurality of other conditions. In order that the various records mademay be distinguished from each other a means is provided to give a characteristic marking to each of the records.

The instrument ofthe present invention is provided with a pair of Vmotors each'one of which, through suitable mechanism, serves to move the recording element across the chart in one direction. Each of these motors is vcontrolled in its rotation by means of an amplier that is responsive to the variationsin a minute electric voltage. This voltage is directly responsive torvariations in the condition being measured, Ysuch, for example, as the voltage produced by a thermocouple if temperature is being measured, or from a tachometer lgenerator if speedvis being measured. The chart upon which the record is made .is drawn with rectilinear coordinates and is man- This application is more speciiically diually moved to bring a new surface under the recording element each time a record is to be made.

It will be obvious to those skilled in the art that any two variables may be plotted against each other such as temperature against pressure, speed against distance, specic gravity against flow, or other variables. This invention is more particularly interested with the recording mechanism, rather than the variables whose values are recorded.

The various features of novelty which characterize this invention are pointed out with parlticularity in the claims annexed to and forming a part of this specification. For a better understanding of the invention, however, its advantages and specific objects obtained with its use, reference should be made to the accompanying drawings and descriptive matter in which is illustrated and described a preferred embodiment of the invention.

In the drawings;

Figure l shows a front view of the instrument with the casing door open,

Figure 2 isa view of the instrument casing with the chassis swung out of position,

Figure 3 is a back view of the mechanism supported on the chassis,

Figure 4 is a top view of the chassis,

Figure 5 is a bottom View of the chassis,

Figure 6 is a view of the paper feeding rolls taken on line S-B of Figure 4,

Figure 7 is a view taken on line 1-1 of Figure 6,

Figure 8 is a sectional View of the chart supporting roll,

Figure 9 isa view taken on line 9 9 shown in Figures l, lland 5,

Figure l0 is an enlarged front View of the pen supporting carriage,

Figure 11 is a top view of the pen supporting carriage taken on line H--II shown in Figures 1 and 9,

Figure 12 is a View of the actuating mechanism for the pen lifter,

Figure 13 is a sectional view taken on line IB-I 3 of Figure ,5,

Figure 14 is a View in section of a portion of the vertical driving mechanism,

Figure 15 is a view of the standardizing mechanism,

Figure 16 is a wiring diagram for the measuring circuits, and

Figure 17 is a view showing the chart record identifying` system.

Referring first to Figures v1 and 2, there is Aopposition to the known voltage.

'e o shown an instrument casing l which is rectangular in shape and which has a door 2 mounted thereon by hinges 3. The door is shown in its open position so that the parts within the casing may be seen. The chart supporting mechanism and the recording mechanism are bothVV swung out of the case, the interior of the casingv will be exposed Vas shown in Figure 2. In this figure there is shown a pair of ampliners li andy I2 that are mounted upon the back or" the casing. Mounted upon the side wall of the casing in line with each other are dry cells i3, one of which is used with'each of tie amplifiers. A series of terminal blocks l@ are also attached to the back of the casing so that the vari-cus electric connections may easily be made. In the drawings the wires which extend between the various parts of the instrument are omitted for the sake ci clearness; the connections, however, are similar to those which are shown in the wiring diagram or Figure l5. The case is deep enough and theparts are so arranged on it and on the chassis that they do not conilict with each other when the chassis is swung into its position in the case.

Each of the amplifying units forms part of a complete potentiometer type circuit of the kind 'disclosed and claimed in the application of Walter P. Wills, Serial Number 421,173, led on December l, 1941, now Patent 2,423,540, issued July 8, 1947. These circuits are, however, connected in a novel manner so that the amplifying unit for one circuit may be used to standardize both circuits. The type of primary measuring element used has not been shown since it is immaterial, and may be responsive to any variable as long as a Voltage varying in accordance with the value of the variable is produced. For example, for vpurposes of this description only, it may be assumed that a graph is being made of temperature plotted against pressure, with temperature as the ordinate and pressure as the abscissa.

The potentiometer circuit or network on the left in Figure 16 is normally connected with the amplifier Il. rihis circuit is provided with a slidewire l5 across which is impressed a potential by one of the batteries i3. As the battery voltage decreases with use the potential may be adjusted to a constant value by means of a variable resist- An unknown voltage proportional to the variable is impressed across the slidewire in This unknown voltage is applied to terminals Il' and i8. From terminal Il connection is made direct to a collector bar i9 and a contact 2l to the slidewire i5. From terminal i8 connection is made through stationary contact 2?., movable contact 23, of a switch 2G, and wire 265 to a center tap on the primary of a transformer forming part of a converter ila that is built into amplifier il. Connection is made from the converter, by wire to a point 2S in the potentiometer network. When the potentiometer network is unbalanced due to a change in the input voltage, this unbalance is detected by the converter and amplified in a manner set forth in the above mentioned Wills application to energize a motor 2 for rotation in a direction dependent upon the network unbalance. As the motor 2l rotates it moves the contact 2| along the slidewire l5 and collector bar I9 in a direction and amount to rebalance the network and simultaneously adjusts a recording element.

The potentiometer network on the right of Figure 16 is similar to that on the left in that it is provided with a slidewire 2&5 across which a known voltage is impressed by a battery ld, the voltage Y being kept constant as the battery diminishes by a rheostat 29. v The unknown voltage is applied to terminals 3l and 32, the former of which is connected directly with a collector bar 33 and movable contact 3d. The terminal t2 is connected through stationary contact 3S and movable contact 35, of a switch 3l, stationary contact 38 and movable contact 39 of the switch 29, wire M, junction 42 and wire i3 to the center tap of the primary winding of a transformer forming part of a converter I2a of the amplier i2. From the converter connection is made through wire 44 to a movable contact t5 and a stationary contact t6 of the switch 2@ to a point il of the potentiometer network. As the network is unbalanced a motor 48 will be energized for rotation in one direction or the other by amplier l2 to shift contact 34 along the slidewire 28 the collector bar 33 to a position in which the network is again balanced, and to simultaneously shift the recording element in a direction at right angles to the direction in which it was moved by motor 2l.

In the normal operation of the instruments the circuit connections are as shown in Figure l5. From time to time, as the batteries i3 diminish in strength the networks must be recali-brated or standardized by adjusting the resistances l@ and 29. When this is done the potentiometer circuits are disconnected from the input terminals il and i8, and 3| and 32 respectively, and have a standard cell 5S connected across a portion thereof. The same amplifier is used for both potentiometer networks during the standardizing operation.

To standardize the left network, the movable contacts of switch 2S are moved to the left by a bar that connects them. When this is done the converter l2ctV and standard cell 5@ are connected in that circuit between points 9 and by a connection including a wire extending from point 5:9 to a stationary contact el, movable contact 52, cell 5G, junction d2, and wire i3 to the transformer of converter 12d. From the converter the connection extends through wire movable contact 45, and a stationary contact 53 to the junction point 26. At the same time this is done a resistance 54 is shunted across the converter 22a. The circuit for this is from junction d2, wire 4I, movable contact Se, and stationary contact 55 to resistance 543 and junction 25. The same operation that moves the contacts of switch 2e to the left is used to close a clutch 5t, so that as motor 48 is rotated due to unbalance of the left potentiometer network the standardizing resistance it will be adjusted by it in a direction to recalibrate the network.

In standardizing the right network, the input thereto is disconnected and standard cell 53 and converter |2a are connected across points fi'! and 51v by shifting the movable contacts of switch el to the right. The circuit for this operation is from point 5l to movable contact 5S, of switch 37, stationary contact 59, cell 5t, junction i2 and Wire 43 to the converter. From the converter the circuit includes wire fit, movable contact .45 and stationary contact 36 to point lil. At the same time a resistance 6I is shunted across the converter by a circuit extending Vfrozii point 41 through the resistance 8|, stationary contact 62, movable contact 38 of switch 31, stationary contact 38 and movable contact 39 of switch 28 and wire 4| to junction 42. The operation of moving the contacts of switch 31 to the right is also used to close a clutch 63 so that rotation of motor 48, due to network unbalance, may be used to adjust the resistance 29 and recalibrate the network.

As the networks rebalance themselves and cause the motors 21 and 48 to rotate, these motors through mechanism to be described later, move a recording'element across a chart. The chart in this case is numbered B4 and is shown as being in strip chart form and upon which are printed a plurality of individual charts made up of rectilinear coordinates. The chart supply 'roll 65, as best shown in Figure 4, is mounted on one side of the chassis 4 while the take-up roll is mounted at 66 on the other side of the chassis. On its way from the supply roll to the take-up roll the chart passes a guide roll 61 ywhich guides it across the front of a platen 68 to a guide roll 69 and a second guide roll 1|. rThus the chart is moved from one side of the chassis to the other across the front of a writi-ng platen which serves to back up the ychart while a record is being made upon it. 'Ihe various resistances and condensers necessary for the potentiometer networks and the standard cell 59 are mounted on suitable supports provided on the back of the chassis 4 as shown in Figure 3. For the sake of clearness, no wiring is shown in that figure.

The supply roll 65 is mounted upon a core which is so designed that a slight tendency to rewind the chart upon this roll is at all times present, which tendency can be overcome by the slipping of a friction clutch when the chart is moved. Thus the chart is at all times held under tension so that the portion thereof in front of the platen will always be taut. As shown in Figure 8, the supply roll support consists of a shaft 12 upon the upper end of which is rotatably mounted an elongated collar 13 and upon the lower portion of which is mounted a second collar 14. These collars serve to support a drum 15 that has rigidly fastened to its lower end a ange 18. The chart supply roll is mounted on the drum 15 and is kept from rotating with respect thereto by means of a spring 11 whose upper end is adapted to be received in the usual notch formed in the core of the chart roll. This spring is attached to the collar 13 by means of a screw 18 and its upper end extends through a notch 19 formed in the surface of the drum 15.

member 85 of a jaw clutch that is attached by a pin 86 to the collar 14. The member 85 has a jaw 81 projecting downwardly from it which is adapted to 'engage a jaw 89 projecting upwardly from a second clutch member 88 that is also freely rotatable upon the shaft 12. These clutch members are normally maintained in the relation shown, in which the jaws 81 and 89 do not engage each other, by means of a torsion spring 9| that has one end projecting into thev clutch member and the other end projecting into the clutch member 88. Engaging the lower surface of the member 88 is a disc 92 of friction material that is pressed upwardly into engage ment with the member 88 by means of a disc 93 that is slidably received on the lower end. of the shaft 12. The shaft at this point is pro vided with flats on its surface with which the disc 93 cooperates so that it will not rotate relative thereto. Clutch member 88, disc 92 and disc 93 are forced into engagement with each other by means of spring 94, whose tension can be adjusted by a nut 95 that is threaded upon the shaft 12.

After the supply roll 65 has been placed on drum 15 with spring 11 in a notch in the roll core, the assembly is placed in position in the chassis (Figs. 3 and 4) with part 82 received in a slot 91 formed in a bracket 96 attached to the top of the chassis. The lower end of shaft 12 is received by an opening in a bracket 98 attached to the lower end of the chassis. The chart roll is maintained in the proper vertical position by a screw 99 that is threaded into the bottom of bracket 98 to limit the downward movement of shaft 12. Washer 83 bearing against the lower surface of bracket 96 under the force of spring 84 assists gravity in holding the assembly in position.

In operation, as the chart is moved across the surface of the platen the chart roll will cause the drum 15 to rotate with it. As the drum rotates it will first move clutch member 85 until the jaw 81 thereof engages the jaw 89 of clutch member 88. Thereafter, the clutch member 83 will also be moved against the friction provided by the engagement between its lower face and the friction disc 92. When the chart has stopped being moved, spring 9| will tend to unwind itself to separate jaws 81 and 89 and thereby place the chart under tension. From the above it will be seen that when the chart is initially moved, the spring 9| is placed under tension and thereafter the chart drum 15 will be rotated against the friction of the disc 92. When the chart is no longer moved, clutch member 88 will remain in its new position and the spring 9| will place the chart under tension.

The take-up roll 66 (Fig. 1) is placed on a drum |0| and is held in position thereon by a flange |82 on the lower end of the drum against which the roll rests. Drum |0| is fastened to a shaft |93 passing through it, which shaft has a collar |84 rotatably mounted on its upper end. In mounting the assembly in the instrument the collar is placed in a suitable holder |65 attached to the chassis with the lower end of shaft |03 in a suitable bearing in the frame. Collar Itil is held in the frame |85 by means of a collar |85 that bears against the bottom of the frame under the force of a spring |81. If desired the take-up roll can be rotated manually by means of a knob |08, but the take-up roll is ordinarily' driven by frictional engagement between its surface and the surface of a friction driving roller I0 The friction drive roll |09 (Figs. 4 to 7) is rotatably supported in an upper arm and a lower arm |I2, which arms are pivotally mounted on a vertically extending shaft H3. In order that the arms may have a good bearing on shaft ||3 each of them has a sleeve attached to it through which the shaft extends. One of these sleeves is shown at ||4 in Figure 6 as being attached to arm I. It is noted that guide roller 69 is also mounted to rotate around shaft ||3 face oi the cup member.

i and is therefore provided with bearings that surround the shaft, one of which is shown in Figure 6 below sleeve H4.

Normally the friction roll |09 is spring pressed into engagement with the surface of the take-up roll 66 so that upon rotation of the friction roll i the take-up roll will be rotated also. To this end a spring is wrapped around the sleeve l i4 and has one end attached thereto, while the other end bears on a portion of the chassis ii. This spring serves to force the arms l!! and l2 on a clockwise direction in Figure 4.

A special construction is used on the upper and lower ends of roll |09 to make sure that there will be sufficient friction between that roll and the take-up roll SS to drive the latter. Since the upper and lower ends of the friction driving roll Aare made in exactly the same manner, only the upper end thereof is shown in section in Figure 6. It will be seen that this driving roll is mounted upon sleeves i I6 that are in turn attached to a shaft iii by means of a set screw H3. The shaft il? is suitably journaled for rotation in arms iii and H2. The upper end of the sleeve il is reduced in diameter as shown, and has placed upon it a number of friction discs l ie that may be made of some material such as composition cork or iibre. These discs are tightly held in engagement with the sleeve l l by means of a nut 52| that is threaded upon the upper end of the sleeve. The discs H9 are slightly larger in diameter than the roller HB9 so that as the roller is rotated, these discs will bear upon the surface of the take-up roll to drive the same. Due to their friction characteristics, there will be no slippage between the take-up roll and the friction driving roll. Y

Rotation is imparted to the driving roll ice by means of a gear |22 fastened to the upper end oi the shaft l il. This gear meshes with a pinion |23 mounted on the arm I, which pinion in turn is driven by gear |214. YAs shown in Figure 6, this gear has a tubular extension that is journaled in the chassis d and which is attached to a bevel pinion |25. rihe upper end of shaft H3 is received by the bevel pinion which acts as a bearing therefor. The pinion |25 meshes with a second beveled pinion 26 that is attached to a shaft |21 which is journaled in bearings |23. In the operation of the device, a knob |29 on the front end of shaft |27 is rotated to rotate the pinion |26, and the various gears forming the gear train between that pinion and gear |22, so that the drum |69 can be rotated to drive the take-up roll.

Normally the knob |29 is rotated in a direction so that the chart will be wound up on the roll 66. In order to prevent retrograde movement of the roll |69, the shaft |21 has mounted on it what is, in effect, a one-way brake. To this end the rear bearing |28 for the shaft |2'l has in it a hardened steel bushing |3| that receives the shaft. Mounted on the outer end of the shaft is a cup shaped member 32 of such a diameter that an annular space is left between this member and bushing |31. Within this space is a coil spring |33 that loosely encircles the bushing and which has one end attached to the cup shaped member. This spring is wound in such a direction that upon rotation oi the shaft |21 in a direction to .feed the chart to roller 6E, the spring will tend to expand into engagement with the inner sur- Upon rotation of the shaft i2? in a reverse direction, however, the spring |23 will grab the outer surface of the 8 shaft m in that direction. From the above it will be seen that since the friction roller It cannot turn in a reverse direction, the spring 3| in the supply roll can pull the chart tight without having a tendency to unwind it from the take-up roll.

At times it may be desirable to tear olf each of the sections of the chart after it has had a record drawn upon it, rather than saving all of these sections in a roll. if this is the case, the chart will be directed from the guide roll ll, as seen in Figure 4, between the drum upon which the take-up roll is normally-mounted and the friction driving drum los, around in iront of that driving roll and behind a cutter member |323. When this typ-e of chart drive is used, the chart is pinched between the take-up roll and drive roll |99 to be fed forwardly below the cutting edge. When the chart has been advanced sufficiently, it may be pulled downwardly against the cutting edge to be torn off in sections. en indicator i3d on the chassis (Fig. l) cooperates with the chart to show when it is properly positioned.

in order to simplify the attaching of the chart to the take-up roll and the threading of the chart around guide rollers te and il, a means is provided to hold the friction drive roll lo@ out of engagement with the take-up roll 55. For this purpose a hook lili) (Figs. l and 5) is fastened to the lower portion of the chassis back of scale 223.

-When a new chart is to be placed in the instrument the friction drive roll |69 is moved clockwise in Figure 5 against the force of spring i5 until the hook illii is engaged behind the bent edge of the cutter bar |36. The friction drive roll will then be held in inactive position until it is released by removing the hook from the cutter bar.

The pen which is used to make a record on the chart is mounted on a vertically movable carriage that is in turn mounted on a horizontally movable frame. Because of this type of mounting the pen can be moved in any direction across the chart to record the varying Values of the two conditions that are being measured. As shown vin Figures 1, lo and 11, the pen 35 comprises an angle member 36 that is Ina-de of thin sheet metal which is bent as shown in Figure lo. The ends oi' this angie member are attached to a frame lSl whose rear ends extend to the right in Figure 1l and terminate at an angle as shown at i3d. A combination reinforcing and pivot pin 39 joins the upper and lower portions of the frame. The writing point for the pen is formed by the end of a piece or capillary tubing Uil which extends rearwardly into engagement with the chart at the angle formed in the member |38. From its writing tip, the capillary tube extends down through the lower arm of the angle member and into a transparent ink receiving container |512. This container or cup is suitably fastened into a holder M3 which is attached to the lower end of the frame |31. The pen frame `is also provided with a forwardly extending part bushing |3| to prevent or retard rotation of the r75 lof the brackets |46. The pen s mounted on the pen carriage, as best shown in Figure 1l, by moving the pen into engagement with the spring |41, and then to the right along this spring until the pivot pin |39 moves under and into engagement with a notch formed in the brackets |46. The pen is then held in position with the pivot pin being pressed into engagement with the brackets |45 by the spring |41 as is best shown in Figure 11.

In order to guide the pen carriage in its vertical movement a block |48 is attached to the cross member of the U |45. This block has a pair of rollers |48 on its upper end and a pair of rollers on its lower end which rollers, along with a third roller |52 located in a vertical position midway between rollers |49 and |5|, engage a vertically extending rod |53.

The carriage is also provided with a pair of front rollers |55 and |55, the latter of which is supported on the pen carriage by means of a supporting member |56 that is attached to the U-shaped member by suitable screws. It is noted that these screws also hold a spring |51 which is adapted to bear against the right face of the part |44 on the pen to force the pen in a clock- Wise direction around the pivot pin |38 into engagement with the chart. Rollers |54 and |55 engage one of the flanges of a channel member |58 which extends in a vertical direction and is parallel to the rod |53. It will be seen that the cooperation of the various rollers with the rod and with the channel hold the pen carriage in a predetermined position relative to the chart so that the pen will at all times engage the chart as the pen carriage is raised and lowered.

Rod |53 and channel |58 form part of a movable frame upon which the pen carriage is mounted, which frame is adapted to be moved transversely of the instrument from left to right in Figure l. The frame, as seen in Figure 9, consists of an upper plate member |59 and a lower casting l5! to which the rod and channel member are fastened. The plate and casting also have extending between them two other rods, |52 and |53. The frame is supported in a fixed vertical position by rollers |55 and |56 which bear against the top and bottom of a horizontally extending rod |61. There is also provided a plurality of rollers |64 which bear against the sides of rod |61 to denitely locate the path through which the frame will move. The upper end of the frame is restrained to move through a given path by means of rollers |68 and |69 which bear against the front and back of a rod |12 that extends transversely of the frame parallel to the rod |51. In order to keep the frame aligned vertically and to make sure that the upper end of the frame is exactly above the lower end of the frame as it is moved across the instrument, the rod |62 is rotatably mounted in the frame and is provided on its ends with pinions |13 and |14 which mesh respectively with racks |15 and |16 (Figure 9) that are attached to the chassis 4 above and below the writing platen. Therefore, as the frame is moved across the front of the instrument, the engagement between the racks and pinions will insure a continued vertical position of the same.

The frame carrying the pen carriage and pen is moved horizontally across the front of instrument by means of the motor 21 in response to unbalance of the left hand potentiometer network in Figure 16. To this end, the motor 21 is .attached to the lower 4part of the chassis 4,

10 on the back thereof, as shown in Figures 3 and 5. As the motor rotates, it drives a pulley |11 through suitable gearing, including a gear |18 that is formed on the pulley. Rotation of the pulley is transferred to the frame by means of a cable |19 which has its ends wrapped around and attached to the pulley |11. The central part of the cable extends from the lower surface of the pulley around guide pulleys lil! and |82, the latter of which is biased in a clockwise direction in Figure 5 by a spring |80 (Fig. 3) in order to keep the cable under tension. Movement of the cable as the pulley I 11 rotates is imparted to the frame due to the fact that the cable is attached to the casting |5| of the frame by means of a block |83 which grips the cable between itself and the casting. A screw |84 is provided for this purpose.

As the pulley |11 is rotated by the motor 21, it is shifted axially so that the cable will be fed on and off of the pulley in a helix. This prevents the convolutions of cable from piling up on one another and binding. In order that the pulley may be shifted axially as it rotates, it is provided, as shown in Figure 13, with internal screw threads |85 that engage similar threads on a shaft |85 around which the pulley rotates. This shaft is held against rotation in its mounting in the instrument. The shaft is mounted by having one end placed through an opening in the chassis 4 and its other end placed in an opening in a bracket |92 that is attached to the chassis, as best shown in Figure 5. The shaft is provided with an enlarged portion |81 on one end which serves to help support the pulley and hold it rigid as it rotates. Extending through the pulley |11 and projecting from both ends thereof is a stop pin |88 that serves to positively limit the number of revolutions which may be imparted to the pulley as it rotates. If the pulley is rotating in a direction to move the frame to the right in Figure 5, the screw threads are such that it will be moved downwardly since the cable will be fed on from the right and off from the left. When the frame has reached the end of its travel the lower end of pin |88 will engage stop |89. If the frame is moving in the other direction or to the left in Figure 5, the pulley |11 will be moved upwardly until the upper end of the pin |88 engages against the stop |98. Since it is necessary that the movement of the frame be limited to exactly the extent 0f the calibrated portion of the chart, one of the stops, and in this case the stop me, is made adjustable by means of a screw lei that extends through the bracket l 82. In adjusting the above described mechanism the pulley |11 is rotated until the lower end of pin |38 engages stop |88. The frame is then attached to the cable with the frame in a position so that the recording tip of the pen is on one edge of the calibrated portion of the chart. The motor 21 is then energized for rotation to move the frame in the opposite direction until the recording tip of the pen engages the other end of the calibrated portion of the chart. This is approximately three and'one half rotations of the drum |11 and its diameter is made so that this is the case. In order te deiinitely limit the travel of the frame at this point the screw |9| is adjusted to move stop |85 into engagement with the pin |88.

From an inspection of Figure 13, it will be seen that the pulley E11 is also provided with openings |93 and ist. These openings are intended to receive the ends of the cable so that the cable 111 ends may Abe clamped .in/the pulleybyscrewstlrat are threaded Ithrough suitableopenings in the pulley that are transverse ftozthem. 7Thecable ends are initially pulled tight yenoughso that spring 18) will 'be under tension therebykeeping the cable taut.

As has been pointedfout .above,;the :movable frame is moved Atransversely-of the instrument when the potentiometer Anetwork is unbalanced. This lmovement continues until y.the :network :is rebalanced, and the'balance point is'determined by the proper position ofcontact 2i :along slidewire l5 :and -collectorJ-.bar is. 'To this end the contact 2i is resiliently mounted on the upper plate l'il of the vframe as shown .in Figure .9. The slide-wire .t5 .and .collector .bar I9 are mountedabove thecontactiin aninsulating block i95 that is in turn fastened :to Ia support v1.9.5. This support .is .'.pivoted `on .a shaft :lai extending transverselyl of the chassis :inisuchza fashion that the slide-wire. and collector :bar are f directly .above the Contact.` Since .it is vnecessary :thatxthesldewire be Agiven some .particular-.positionabove the contacts, stop nuts Llf :are .threadedon-the yshaft i9? to Ipositively position thelef't end .of the support 'ist as is shown yin-Figure 4. The frame 195 is definitely llocated above the contact by engagement between :projections E98 extending from each end thereof and the upperrsurface fof the chassis il, and is 4kept in this position by ascrew 29! which engagesthe `right extension Iii-9. In order to clean .the slide-mire Yfrom "time -to time the frame may be swung around shaft i9?! .as Aa pivot after screw '29| has been jremoved. This positions the slide-wire :support so thattheslidewire'isV facing upward zin .an .accessible position.

rihe pen carriage is moved vertically zon the shiftable frame Yby the anotorvi in response to unbalance of the right .hand potentiometerxnetwork in Figure 16. For .this purpose, the Amotor is mounted on the :lower 'portionof the chassis and .over to one side :beyond 'the travel of the frame. As bestzshowningFigure 14,`the motor drives a shaft 1202 whichis receivedin a housing 293. AThe outer-end-of the shaft :has 1a spiral gear 291i onit which meshes-with asimilar .spiral gear fastened to :.a splined shaft i265, the latter shaft extending transversely across the lower portion or the chassis :of `the instrument and journaled for rotation therein. It-.is noted that the shaft 2st is provided :suitable thrust bearings. 2&6 `.and :2.9i and that. :the shaft 265 4is provided *with similar bea-rings which ar-.e not numbered. As lthe splined shaft ZEE rotates, it rotatesfa 'pulley 2st, as shown'in Figures 5 and 9, which pulley is slidably received on the shatii and is moved along theshaft'as the :framezmoves by portions ofthe casting iti lwhich .engage .its sides. `rIhe pen carriage'is'raised'and lowered 'by a cable 299 which has its ends `fastened. to pulley Z. The center portion'of the `cablepasses over` a pulley Zit as-shown in Figure 9, which pulley is mounted inthe upper :portion Aorthefrnovable frame by means `of a vpair of angle Ybrackets '2li that are located on top of the plate |53 by means of pins 2HE. Pulley'Zltl is normally biased in an upward direction in order to maintain the cable 2HE under tension by a vpair of springs 2 |13 which surround the pins'igand are located between the upper surfacel of plate l'59 and the lower surl face of the angle vbrackets til.

'.'Uribalance of the #potentiometer .network causes the motor 'ftotart :rotating :to raise-.or lower 4:the 4-pen carriage. When the potentiometer vnetworkiias been rebalanceclfthe :motor -will stop rotating. To this .-end the contact 3s ,is attached togthezside of the-pen carriage and extends into.'engagement'withgthe slide-wire' and collector bar 2;8 thatfare vmounted :on averti'cally positioned insulating block Zit. lThis block is fastened toa supportz Il thatis pivoted to move around the shaft 183. Normally the support .is held in the position shown ini-Figure l1 by means of Ya latchzincluding 1a .-nger i2 t8 that is .slidably mounted on the support and which nngerengages the 'turnedup ,edge of abracketEI-B that is attached to the channel 1:58. The resiliency of the contact 34 .-bearing against the slide-wire tends to move-thefsupport 2iin a-counter-clockn wise -directionzinjlfigurell until the latch 218 engages :the bracket -2l9. lln vthis manner the slide-wireis.xdenitelyjpositioned relative to the contact. LBymovingfthe la-tch v248 upwardly in Figure Il, its'lower end will be brought out .of engagement Y.with the bracket 2 lefand the entire slide-wire assembly may be moved to a position in which itis accessible for cleaning.

lt is noted that the -holder IE6 v-for Yroller IE5 serves as =a pointer to indicate-the lposition of the carriage `along a scale-22 tthat is attached to the front :portion of the channel member i158 and the bracket'Ei-S. Itis also noted that the frame has on-it a l.pointer 2272 which'cooperates with a scale 223 that-extends across the lower portion of the instrument to show the position of the frame with respect to therchart. The scale 223 is attached to a frame member 221i that is pivotedon the lower part of `thechassisf-at 225. Thus the frame andthe scale Ycarried vby itmay bemoved in-a clockwise fd-irection in .Figure =to give access to the mechanism on the lower part .of the chassis.

Astopiis provided todim-it the rotation of motor 48 so thatthepencarriage may not -be moved above .or -below the v:calibration marks on the chart. To this end, as seen in fligure 1.4, .a drive member ,22d is formedas aprojection on the pinion 225i 1 that .is placed cnthe motor shaft. Rotatable gon the shaft 2.0i and reading from left to right area series of `par-ts that `are driven by the .member 225 and .which serveto act as a stop to `limit nrotation .of the Shar-h2g2. These member-s are, part 228. having..a lug V229 extending upwardly therefrom, vvvbent member 123i, one .end .of which eX-tends -to the right andorre vend of c which extendstothe left. There isalso a second part '232 Yhaving vra lugr 2.33,.,a second bent member 2311, a .third part -havingalugZ-d; anda third bent .member 237. It will be seen that .as the shaft 2%2 .is rotated, the @drive member Y225 will move part 228 until .its lug.u 22S; engages one bent overportion of `member 231.. The latter Vmember willthen-be-driven by part 228 and Vits bent over end extendingto the Vright willengage the lug 233 onpa-rt 232 tordrive thezlatter. In this manw ner, one -of these members` after the other will be picked up until suchtimeras the arm extending from the right of member 23? engages the lower end -of a screwv that :extends into the housingi293. This-positively stopsthe shaft Upon a kreverse rotationof the motor HS, the various parts will be picked Aup in sequence and rotated tin the opposite direction until the member 25? engages the otherside of .screw 233 to positively 4stop the rotation of the .sha-ft in that direction. `The screwrzisormed with a conisleeve engages behind the projection cal end so that by moving it further into or out of the housing 203 the shaft 2M will be permitted to rotate more or less. This is an adjustment which Will permit a definite limiting of the end of the movement of the pen carriage with the writing tip of the pen at the edge of the chart calibration marks.

When moving the chart from beneath the pen after a record has been made, it is necessary to lift the pen up away from the chart so that it will not make an undesirable line thereon. lThis may be done by moving a bar member 229 in Figure 11 clockwise around shaft 122 into engagement with the rear ends |38 of the pen frame. Such engagement will pivot the pen around shaft 139 and raise its writing tip out of engagement with the chart. The member 239 consists of a bar which has its ends bent over as shown in Figure 9 and perforated so that they may be received by the shaft |62. This bar is located vertically along the shaft by means of a collar 213i that surrounds the lower part of the shaft and extends between the bar 239 and the pinion |14. The bar is rotated around shaft 162 by means of an eccentric 242 which is received between the arms of a yoke 243 that is attached to the upper end of the bar 239. Rotation is imparted to the eccentric by a shaft 244 upon which it isslidably received, the shaft extending transversely of the chassis. on it so that as it is rotated, the eccentric will be rotated. rIfhe frame is provided with a pair of brackets 2i5 that are attached to the lower surface of plate l59, which brackets engage the ends of the eccentric to move it along shaft 244 as the frame moves.

Shaft 244 is held in its rotated positions by means of a mechanism which is shown in detail in Figure 12, and which is mounted on the upper right hand portion of the chassis. With reference to Figure 12, it will be seen that the shaft 244 has a pinion 24% on its end, which pinion engages a rack that is formed on the upper surface of a sleeve 2511 received in a suitable bracket on the end of the chassis. Extending through and supporting the sleeve is a shaft 26rd which shaft is journaled in the bracket. rEhe sleeve 241 and its rack are normally held in the position on the shaft 228 that is shown in Figure l2, by means of a spring 22S which surrounds the shaft and which bears with one end against an enlargement 25! on the sleeve and with its other end against a 252 on the shaft. The assembly consisting of the shaft and the sleeve may be moved to the right from their normal position shown against the tension of a spring 253 that bears with one end against the bracket and with .its other end against a push button 254. rfhe left limit to which the shaft can be moved is determined by a stop 255 that engages the head 252 on the shaft. A catch to hold the sleeve in its right position is provided by a lever 255, which is pivoted at 25? and which is biased in a counterclockwise direction in Figure i2 by means of a spring 25S to a position limited by engagement between the opening 25S formed in the lever and a pin 2%5 projecting from the chassis ii. Lever 25d has formed on its upper surface a projection 222 and has pivoted at on its right end a pawl This pawl is biased in a clockwise direction by a spring 25? to bring a rin 265 on it into engagement with a pin on the lever.

In the operation of this mechanism, the button 254 is pushed to the right until head 2.5i on the 222 on lever It will be seen that the shaft has a flat 14 256. In this position shaft 244 has been rotated and, through eccentric 242 and yoke 243, the bar 239 has been moved so that it is against the end i38 of the pen frame. The writing point of the pen is therefore moved out of engagement with the chart. When the button d is again pushed, the head 253 will bear against the upper end of pawl 263, camming the lever 232 in a clockwise direction in Figure l2 far enough to permit the projection 252 to move below the head 25i. When this happens, spring 228 will move the sleeve and its rack 221 to the left rotating shaft 242 so that the bar 239 will be moved away from the ends 38 on the pen, permitting the pen point to move toward the chart under the force of spring 151. It will be seen that if the button 254 is pushed all the way, head 252 will move the lever 25% clockwise while 25| moves to the right of projection 282. On the return movement of shaft 248, the left face of the head 252 will engage the right face of pawl 263 and rotate the latter against its spring tension around its pivot 255,. Since the lever 255 is not moved, shaft 222 returns to the left and head 25| will stay behind the projection 262. Thus it will be seen that a movement of the button 254 all the way to the right will operate the mechanism to lock head 25! behind the projection 252 and raise the pen from the paper while movement of the button 254, only a portion of the way to the right, will effect the release of the sleeve 241 so that the pen will be moved against the chart.

As was pointed out above, the instrument must be standardized from time to time to compensate for decrease in the voltage of the batteries I3. This is done by connecting the standard cell 5] into the circuit and by adjusting the rheostats i6 and 22 to recalibrate the potentiometer network. The rheostats l and 29 are similar in construction and are mounted on the back of the chassis near the bottom thereof. This construction is shown in detail in Figure l5 wherein it will be seen that each of the resistances is of the so-calied Vernier type and comprises a fine winding 2GB and a coarse winding 229 that are mounted on discs which are rotatable around a ,shaft 21l. These windings are adjusted with respect to contacts 21B by means of a gear for resistance I6 and a gear 213 for resistance 2S. The gear 212 is provided with a rod 214 that projects therefrom through a hole in the disc for winding 262 and through a slot formed in the disc for winding 269. In this fashion as the gear H2 is rotated, the winding 228 will be moved immediately but the winding 269 will not be moved until after the rod 214 has been moved through the length of the slot formed in its disc. Thus upon the adjustment of the rheostat the coarse winding will not be moved until the adjustment provided by the fine winding has been used up. gear 213 is provided with a pin that cooperates with the discs upon which the resistances of the rheostat 29 are wound.

The gears 212 and 213 are rotated by means of gears 216 and 211, respectively, which are rotatable around a shaft 218 and which are maintained in their position relative to the gears 212 and 213 by holding members 22S and 223i respectively. These members are attached to the framework and engage in grooves formed in hubs of the gears. Shaft 218 is rotated by the motor 48 through gearing which extends between the pinion 221 of the motor shaft and a lgear 222 which is mounted on the shaft 218. Rotation of the shaft 218 is imparted to the gears 216 and 211 by meansof the-clutchestl and .63 that have been mentioned ,.above. .These clutches consist of discs that are keyed to and slidable on the shaft 218 and which are resiliently pressed. toward the outer face of the Vgears 216 and 211,. respectively, by springs 283 and 23d. The op-A posite ends ofv these springs are held in position on the shaft by suitable collars. Shaft Y2121s moved axially to the left to bring clutch disc 55 into engagement with the face of gear 216 by means of a shaft 285 that is `iournaled in a suitable frame 255 attached to the chassis. This shaft 285 is normally held in its position shown by means of a spring 281 that surrounds the shaft 285 and is received in a recess in the frame. 286. This spring bears against a button 282 on the outerend of the shaft 285. Connection is made between the shafts 285 and 218 by means of a collar 289 that isattached to the end of the shaft 218 and which receives the end of shaft. 285. Asbest shown in Figure 15, the shaft 285 is formed with a groove in its end, whichgroove receives a set screw 29! extending through the collar 289. By means of this connection, axial movement may be imparted to the shaft 218 but that shaft can rotate without rotating shaft 285. Shaft 218 is moved to the right to bring clutch disc 62 into engagement with the adjoining face of gear 211 by means of a shaft 292 that is alsol journaled in the frame 286. The shaft 292 ist held in the position shown by means of a spring 293 that engages with a button 2913 formed on the end of the shaft. vIt will be seen from the drawing that shaft 292 is formed on its upper side with a rack that meshes with a pinion 255 that also meshes witha rack formed on the lower side of shaft 285. Thus, when the button 251% is pushed to the left, pinion 295 is rotated clockwise and the shafts 235 and '218 are moved to the right to close clutch E3.

In order to properly standardize the instrument, it is necessary to simultaneously shift the switch 22 when clutch 55 is closed and shiftthe switch 31 when clutch 53 is closed. The left end .of shaft 2 92 is used for this purpose. Referring to Figure 5 of the drawing, it will be seen that this shaft is formed with a cam surface 295 that will move the switch operating button 252 to the left when shaft 292 is moved upwardly in Figure 5, or to the right'in Figure 15. Shaft 252 is also formed with a cam surface 291 that will move the actuating button 299 for switch 31 to the right when shaft 295 is moved downwardly in YFigure 5 or to the left in Figure l5. Thus it will beseen that when the buttons are pushed to close clutch 55, switch 29 will be thrown, and whenV clutch 63 is closed switch 31 will be thrown. -Any unbalance in the potentiometer circuits clue to diminishing battery voltage will be compensated for by the motor 48 as it rotates and adjusts the resistances i6 or 29 respectively.

At times it may be desirable to have several records on one chart, for example, to plot several pressures against a single temperature. If so, some means of identifying the various records is required. This can be accomplished by 'giving a distinctive jog or movement to the pen as it moves across the chart in making each reccrd. Figure 17 .shows the kind of records that may be made yfollowing this method. For example, record. A is a single straight line that does not. have any interruptions in it. Record .B is a line that has single humps or jogs made in it as the pen .crosses the calibration marks for 20, .40 and 60. Record C has similar humps in. it when. .the pen .crosses record marks .for

10.,.30and 50. .RecordDhas double .humps in it as the pen crosses calibration marks 20, .40 .and 60. vRecord Ehas .double humpsinit as thepe crosses one of 4the calibration-markslO, 30 and 50. RecordF has a hump .made in it each time the pen crosses one of the calibration marks `10 to 60 inclusive. This may be accomplished by paralleling one of thecalibrating resistances in the potentiometer network that controls the vertical movement of the pen with another resistance 3D2. The resistance 302 can be made adjustable, and .in this way the height of the humps placed in the various .records may bead- Vjusted` The instrument is manually connected to the six pressures by any suitable means and at the same time a switch V.shown in Figure 16 is .adjusted. This switch has twelve contacts, a to Z inclusive, which contacts are connected by means of a brush-323 to a commutator shown generally atf34. This commutator, as is shown-in Figures 3 and 5.,V is mounted on the lower rear portion of the chassis i of .the instrument and is driven through gearing `3i5 by the motor 21 that moves the pen in a horizontal direction. The commutator consists of .three rings 325, 325 and 351, the first'two of which are engaged respectively by brushes 308 and 309 on one side and all three of which are engaged by brushes 3| l, SI2 and 3l3 respectively at diametrically opposite points. These commutator rings are mounted on a shaft Sil-i that is journaled for -rotation in thechassis li and is driven by the above mentioned gearing 3 l 5. The brushes are insulated from each other and from the chassis by being mounted on an insulating block 3 l@ that is held in place above the commutator by `a bracket 3H.

Referring to Figure 16 of the drawing it will be seen that ring 321 of the commutator is conducting around its entire surface. YRing 326 is conducting for only a short length of its surface and ring 305 is formed with a similar short conducting surface that is displaced circumferentially by a small amount from the conducting surface on ring 355. The conducting portions of rings 305 and 305 are electrically connected to ring 321. The conducting portions of rings 355and B are also placed with respect to the contacts engaging them and with the motor 21 that they will be engaged by contacts 35S and 559 as the pen passes calibration marks 10 and 30 and 50 across the chart, and will be engaged by contacts 3 Il and SI2 as the pen passes calibration marks 20, and 60 across the chart. Y

If record A is to be made, brush wiilbe shifted to engage contacts a and g. Since these contacts are not connected to anything the resistance 32! will not be disturbed and a smooth line will be drawn. If record B is to be made, brush 553 will 'engage contacts b and 7i, the latter of which is connected to brush 352. Therefore as the penis moved and the commutator rotated resistance 322 will be placed .in parallel with resistance 35i when the penis at 2s, e@ and across the chart so that a hump will be placed in the record at these points. If record E is to be made, brush 323 will engage contacts c and i that are connected respectively to brushes 522 and 325. Therefore, when the conizcting portions 355 and 356 Apass under the brushes 323 and 329 as the pen crosses calibration markslO,

V3() and 50 on the chart resistance 352 will be placed in parallel with resistance 52E to put humps in the record as shown in Figure 17. Rec

l? ords C, D, and F are made in similar fashion. When record C is made brush 333 engages contacts Z and f. When record D is to be made brush 3D3 engages contacts d and i, and when record F is to be made brush 303 engages contacts c and lc.

The general operation of the device should be apparent from the above detailed description. The instrument is adapted to make a graph of two variable conditions, and in so doing uses two potentiometer networks, one of which is unbalanced as the vertical component oi the graph changes and the other of which is unbalanced when the horizontal component of the graph changes. Thus, the pen can be moved across the chart in response to variations in the variables. The instrument is compact and the various parts are readily accessible for adjustment and repair.

While in accordance with the provisions of the statutes, I have illustrated and described the best form of this invention now known to me, it would be apparent to those skilled in the art that changes may be made in the form of the apparatus disclosed without departing from the spirit of this invention as set forth in the appended claims, and that in some cases certain features of this invention may sometimes be used to advantage without a corresponding use of other features.

Having now described this invention, what I claim as new and desire to secure by Letters Patent is:

1. In a recording instrument having a stationary chart upon which records of the values of several conditions may be made, a recording element, iirst means to move said element across the chart in response to the value of any one or" several conditions, second means to move said recording element across the chart at an angle to the direction in which it is moved by said rst means, and means correlated with the position of said element to operate said second means at predetermined points in the path of said element as it is moved by said first means, said predetermined points being diierent depending upon which of the several conditions said element is recording.

2. In a recording instrument having a stationary chart upon which the records of the values of a plurality of conditions may be made, a recording element, a rst means operable in response to the value of any one of a number of conditions to move said element across the chart, a second means to move said element across the chart at an angle to the direction it is moved by said nrst means, means correlated with the position of said element to operate said second means when said first means has moved said element to various predetermined points across the chart depending upon which condition said first means is responding to.

3. In a recording instrument having a stationary chart upon which records of the Values of a plurality of conditions may be made, a recording element, a rst means to move said element across the chart, mechanism to operate said means in response to the value of a condition, a second means to move said recording element across the chart at an angle to the direction in which it is moved by said iirst means, actuating means for said second means, means to synchronize the operation of said actuating means with the operation of said mechanism whereby said element will be moved at said angle at predeter- 18 mined points across the chart, and means to change said predetermined points depending upon what condition said mechanism is responding to.

4. In a recording instrument having a chart upon which the record oi the value of a condition may be made, a iirst balanceable electrical network operative to be unbalanced in response to variations in the value of the condition, a recording element, a rst means to move said recording element across the chart in response to unbalance of said rst network, a second balanceable electrical network, means operated in response 'to unbalance of said second network to move said element across the chart at an angle to the direction it is moved in response to unbalance of said first network, and means synchronized with the operation of said iirst means to unbalance said second network a predetermined amount when said element is at predetermined points across the chart.

5. In a recording instrument having a chart upon which records of the Values of a plurality of conditions may be made, a recording element, a first means to move said element across the chart in response to the value of any one of a plurality of conditions, a balanceable electrical network having resistors in it, a separate resistor, means to insert said separate resistor in parallel with one of said network resistors to unbalance said network, means responsive to unbalance of said network to move said element at an angle to the direction in which it is moved by said rst means, a commutator, brushes cooperating therewith connected to said resistors to connect said resistors in parallel as said commutator rotates, means to rotate said commutator by said rst means, and means to connect said commutator and said brushes in different circuits to vary the times at which said resistors are placed in parallel.

6. In a recording instrument, a rst balanceable electrical network including a rst slidewire and a contact movable thereover to a position in which said network is balanced, a second balanceable electrical network including a second slidewire and a contact movable thereover to a position in which said network is balanced, a frame movable through a path, means responsive to unbalance of said second network to move said frame through said path, said second slidewire being mounted adjacent said path and the contact therefor being mounted on said frame so that the contact will be moved along the slidewire to a position in which said second network is balanced, a carriage mounted for movement on said frame in a direction at an angle to said path, the slidewire for said rst network being mounted on said frame parallel to the path of movement of said carriage, the contact for said first slidewire being mounted on said carriage for movement therewith along the slidewire to a position in which said first network is balanced, and a recording element carried by said carriage whereby it will be moved to a position dependent upon the balanced position of said two networks.

7. In a recording instrument, the combination of a frame, means to move said frame through a path to positions proportional to the value of a variable condition, guide means on said frame, an elongated resistance element pivoted to said frame and extending parallel to said guide means, a carriage mounted on said frame for movement thereon through a path guided by said guide means, a recording element pivoted to said carfacce-,eac

-ifiaga'mea'ns on said carriage to bias said-re- 4vco'rding element in Aa direction-toward a chart vupon which it is to make a record, a contact mounted on said carriage and extending toward said resistance element, means to hold normally Asaid resistance element in a position to engage said contact as said carriage moves, and means to move said carriage to various positions along -s'ai'd frame in response to' variations in a second varia-ble condition.

8. In a recording instrument, the combination Vof a frame, means to move said frame through'a path to various positions,'guide means on said frame, a carriage mounted on said guide means, means-to movesaidcarriagel to various positions `along said frame, a recording element mounted on said carriage, a contact mounted on and extending outwardly from said carriage, an elongated resistance, means to'pivota'lly mount said resistance on 'saidframe so that it extendsparallel to said guide means, and means to hold normally said resistance in position to be engaged 'by said contact as said carriage moves.

9. In apparatus for recording the values of a plurality of variable conditions on a stationary chart, a irst balanceable electric network operative to be unbalanced in response to variations in the value of a selected one of the conditions, a recording element in continuous contact with the chart, a rst motor operative to move said element across the chart in response to unbalance -cf said rst network, a` second balanceable electric network, a network-constantevarying coniponent operative to unbalance saidv second network when connected thereto, a second motor operative to move said element' across the chart at an angle to the direction in' which lit is moved in response to imbalance of saidV first network and to thereby make an identifying mark in the graph 4traced by said element, said second motor being responsive to unbalance of said network, and lan electric#circuit-maker-and-breaker mechanically connected to said rst motor so as'to be driven thereby to circuit-makingeandicircuitlbreaking positions so as tovconnect Aandl disconnect-'said component to and fromsaid'second network.

10. In apparatus for recording the values of a plurality of variable conditions fon'a stationary chart, a nrst balanteablel electricnetwork operative to be unbalanced in" response to variations in the valuek of a selected o'ne of thel"conditions, a recording-'element in continuouscontact withA the chart, a first motor operative tof move said/element across the chart in response to 'unbalance -of'said first network, a second balanceable electric network, a network-constant-varying' component operative to unbalance said second network-'when connected thereto, -a second Ymotor operativeito `move said element across the chart fat an angle to the direction in which it ise mved in response to unbalance of said first network and to'thereb'y make an'identifyingmark in the-,graph'traced by said element, said second motor being responsive to unbalance of said second`network,ran electric-circuit-maker-and-breaker' mechanically connected to said rst motor'so as to be" driven thereby to circuit-making-andlcircuitebreaking positions so as to=connect andfdisconnect said component -to i vand `from said-second network, and nianuallyvoperable mechanism forrselectively Lvarying the circuit-makingeandIbreaking Apositions of said -circuit-maker-andebreaker.

fili. Infapparatus' for recording the values-rota plurality/'of variable f conditions 'onfai stationary chart, a first lcalanceable electric' -networkfoper- `ative to be unbalanced in response to" variations in the value of a selected one of the conditions, a recording element in continuous contact with the chart, a'iirst motor' operative to move said element across the chart in response to unbalance of said nrst network, a second balanceable electric network, a network-constant-varying corn- `ponent operative to unbalance Said second network when connected thereto, a second motor operative to move said element across the chart at an angle to the direction in which it is moved in response to unbalance of said first network and to thereby make' an identifying -markin the graph tracedby said element, said second motor being responsive to unbalance of said second network, an'electric circuitemaker-and-breaker mechanically connected to. said nrst motor so as to be driven thereby to circuit-makingand-circuitbreaking positions so as to connect and disconnect said component to and fromsaid second network,

' and a vsecond electric-circuit-maker-and-breaker manually operable to select contacts of said nrst circuitmakereandecircuit-breaker and 'to connect said contacts in series with said rst circuit-maker-and-breaker.

12. InA apparatus for recordingv as a graph onfa stationary chart the'values of each of aplurality of variable conditions, af irst balanceable electric network operative to be uri-balancedY in response to variations in the value of a selected-one of said conditions, a recording' element in continiious engagement with the chart, a iirst motor operative to move said element across the chart in response vto unbalance of said nrst network, aseoond Vbalanceacle `electric network, networkconstant-varying component operative' to' unbalance said second network whenconnected thereto,

a second motorroperative to move-said `element pen movable lacross thel surface off: s'aid l chart in continuous con-tact therewith, a first Amotor rnechanically connected tosaid'izaento nieve' it in one direction, a secondrnotor mechanically connected to said. pen to move itinI a direction at an angle to the direction in `which it is moved Vby said nrst motor,l periodically moer-atingI means mechanically cfcnnected'toand' driven by said rirst motor to acti-vateand inactiva-te saidsecond motor, and manually operablemeans-operatively connected to said periodically operatedfrneans -so as to vary theti-mes at-whichiy said :second motor is activatedandf inactivated.

14.- In apparatus for recording in sequence on Aav single chart the valuescf each' offra-plurality of variable conditions,A each conditionihavingfa different characteristic, eachfrecordbei-ngi a continuous line graph, recordingmeans moved across the chart inv continuous contact therewith V`in response to a selected `one cffsaid conditions; and `means selected inV crnrespondencev with the condition .'being: recorded fand operable to move said `recording means continuousy contact with l said 21 chart at an angle to the direction in which said recording means is moved in response to said selected condition to place an identifying mark in the record of the condition being recorded.

15. In apparatus for recording successively the values of each of a plurality of different characteristics, recording means for recording the values of a characteristic by a continuous line, selecting means for connecting in succession each of a plurality of characteristics to said recording means, and identifying means responsive to said selecting means to move said recording means at an angle to the direction in which said record'- ing means are moved in response to said characteristic to place a mark identifying the characteristic being recorded in the line forming the record of that characteristic.

GEORGE W. BARNES, JR.

References Cited in the le of this patent UNITED STATES PATENTS Number Name Date Sprague Nov. 18, Holt Oct. 16, Alexander et al Oct. 2, Gasiorowski Oct. 16, Harrison Dec. 9, Grisdale May 24, Woodson Mar. 24, Wilson Oct. 30, Magee Jan. 1, Gruss Jan. 15, Andre Nov. 29, 

